Electrode means



Nov. 5, 1940. J. P'rzoLD ET Al.

ELE'GTRODE MEANS Filed Nov. 28, 1934 o a Z9/We INVEINTORSJo/zdfmesatzolc/ Pcm Betz ATTORNEY,

Patented Nov. 5, 1940 UNITED STATES ELECTRODE MEANS Johannes Ptzold,Erlangen,

and Paul Betz,

Buckenhof, Germany, assignors to the firm Siemens Reiniger WerkeAktiengesellschaft,

Berlin, Germany Application November 28, 1934, Serial No. 755,198 InGermany March 20, 1934 6 Claims.

Our invention relates to electrode means and is particularly concernedwith electrode structures and arrangements for applying medicaltreatment with electric oscillations of very high frequency, on theorder of 25 million cycles per second, for example.

Before describing the invention, we will furnish below a brief review ofthe art and of the underlying principles so that the invention may bereadily understood and appreciated in all its objects and features.

' Electrode arrangements for the purpose intimated above aredistinguished'from the so-called current or contact electrodes employedin diathermy by the provision of a layer of insulating material which'isinterposed between the metallic electrode and the subject to be treated.Early structures of this character employed for an insulator a layer ofCelluloid or rubber which was just a few millimetres deep. Compared withthe customary current or contact electrodes, the use of these structurespresented rthe advantage of carrying out the high frequency treatmentwithout producing burns which may be caused in the case of contactelectrodes by poor contact between -the electrode and the subject.However, the heating eiect which could be obtained bythe use of suchelectrode arrangements was limited substantially to the surface of thesubject to be treated.

It was found subsequently that the heating of deeper/strata, i. e., amore uniform heating of the subject, could be accomplished by usingeither the current or contact electrodes or the above The resultsobtained by the use of such electrode structures seemed to indicate thatthe penetration increases with increased distance of the metal electrodefrom the subject. However, an arbitrary increase of .the distance fromthe subject or, rather to say, increase of the space between the subjectand the electrode structure is not feasible for several reasons. In thefirst place, the total capacity of the treatment ar-ii (Cl. 12S-413)rangement, which is composed of the capacity of the subject and theseries capacities formed by the air space, decreases with increased airspace and finally becomes so small that the treatment circuit cannot betuned to the wave length of the oscillations employed. Anotherconsideration resides in the output of the customary generators, that isto say, in the inability of the generator to supply the required highfrequency energy to lthe subject under treatment beyond a given distanceor air space between the electrode and the subject.

As a result of these difficulties, electrode ar- -rangements were againemployed for the 4treatment in'the condenser eld in conjunction withgenerators of average capacity, wherein a relativelythin layer of a fewmillimetres depth, consisting of insulating material, for example, ofsoft rubber, was provided between the metal electrode and the subject.

In order to increase the penetration in the case of electrodes of thischaracter, the suggestion was made to provide, in addition to therelatively thin rubber layer an auxiliary layer of fibrous insulatingmaterial, such as felt or `the like, i. e., to interpose between themetal electrode and the subject under treatment an insulating materialcontaining ai-r. The use of this material was proposed in order toapproximate the conditions of the corresponding electrode structures tothe conditions of those structures wherein only an air space is providedbetween the metal electrode and the subject to be treated and,accordingly, in order to obtain approximate results.

Our invention is based on the recognition of the concept that'theassumptions previously applied in the construction of electrodearrangements for high frequency .treatment in the condenser field werewrong. As explained previously, and disregarding the-cases where alimited penetration and the provision of an air space are indicated forother reasons, prior investigators assumed that the provision of merelyan air space between the metal electrode and the subject under treatment.was most preferable. We believe this assumpcourse of the lines of theelectric field in a manner undesired to the treatment.

We have found that the penetration increases with increased distance ofthe metal electrode 5 from the subject because the electric fieldexhibits a strong stray effect in close proximity to the electrodeswhile it is relatively uniform only in the central range between theelectrodes. It follows that if the metal electrodes are arranged closeto the surface of the subject under treatment, the density of the fieldwill be considerably greater on the surface of the subject than in thedeeper strata and, consequently, a stronger heating effect will beobtained on the surface.

Conversely, if the distance between the electrodes and the subject isincreased, the surface of the subject is progressively removed from theregion where the stray effect is manifest and is increasingly broughtunder the influence of the relatively uniform region of the field whichis present between the electrodes.

We have also discovered that sufiicient high frequency energy forcarrying out the medical treatment could frequently not be supplied tothe subject with the use of the known electrode means wherein aconsiderable space substan-I tially lled with air was provided in orderto accomplish the expected improved penetration, because this spacerepresents a prohibitive resistance for the high frequency oscillations.This will be apparent when it is considered that the space forms a verysmall capacity due to the small dielectric constant of the medium (airor' felt) disposed therein.

As a further result of our investigation we found that the seriesconnection composed of the air space and the subject, that is to say,the series relation of a medium with a very small dielectric constant(air=1) and a medium with a relatively high dielectric constant(biologic tissue=80 causes a marginal distortion of the eld between themetal electrodes. The lines of force of the electric field are deflectedupon transfer from one medium to the other according to the lawgoverning the passage of lines of force through media of differentdielectric constant, i. e., they bend from the normal upon transitionfrom a medium with small dielectric constant to a medium with highdielectric constant.

Accordingly, in the case of a series relation of air or air containingmaterialand a biologic tissue, the change in the direction of the linesof the field is so great that they proceed immediately underneath -andalong the surface of the tissue, even incident to a relatively smalldeviation from the normal. This may be the reason for the extraordinaryheating of perspiration layers forming upon the surface of the subjecttreated in the condenser field with electric oscillations of very highfrequency.

As noted previously, our invention is concerned with novel and improvedelectrode arrangements and structures wherein the above mentioneddrawbacks are avoided.

One object relates to the provision of a new electrode structure andarrangement wherein the thickness of the intermediate layer between themetal electrode and the object to which the electrical oscillations areapplied is rather great, and

preferably at least 10 mm. in depth,'having a dielectric constant whichis relatively high, that is, as high as possible under any givencircumstances, and wherein the material used for this intermediate layeris of a non-fibrous and air- U free structure.

Another object of the invention is concerned with the provision of anintermediate insulation layer in the new electrode structure, thedielectric constant of which is greater than 10.

The dielectric constant of the intermediate 5 layer may be chosen so asto approximate that of the object to which the electrical oscillationsare to be applied; for example, in the case of treating tissue it may be80 or higher. Accordingly, it is another object of the invention to 10provide a new electrode structure, wherein the dielectric constant ofthe intermediate insulating layer is approximated to that of the object.

Other objects and features will appear as the following descriptionprogresses. 15

The layer may consist of a mixture of water and glycerine having adielectric constant of 20 to 30; or it may consist of distilled waterhaving a dielectric constant of about 80. Suitable substances may alsobe combined to form the in- 20 sulating layer. Thus, mineral insulatingmaterial containing an addition of metal or metal combination may beused. The layer may also be made of high grade ceramic materialcontaining oxide of a heavy metal. Substances such as 25 known asCondensa consisting of steatite with an addition of titanium oxide('IiOz) and other materials of this class known under the names CondensaC and Kerafa may also be used for the purpose of forming the layer.electric constant of Condensa and Condensa C is 40 and 80, respectively,and that of Kerafar is about 100. Other known and suitable insulatingsubstances made of mineral insulating materials, e. g., those knownunder the $5 name Mycalex" which consists of mica and lead borate, andother materials of this class known as Calan, Calit, Frequentit may beused to advantage. Water, oil or liquid materials having kindredproperties may also be employed. 40

Since from the point of view of treatment the insulating materialinterposed between the metal electrode and the subject must bedeformable, it is desirable if solids are used to employ them inpowdered form. The powder may, conven- 45 iently be enclosed in aninsulating casing for instance of rubber, the walls of which are thin incomparison with the depth of the powder layer.

When fluid insulators are used, it is desirable 50 similarly to enclosethese in a deformable insulating casing of rubber or the like.

It is also possible to employ relatively yieldable or plastic insulatingmaterials such as wax and the like for use between the electrode and 55the subject, as previously intimated.

In view of the fact that some of the insulating materials suitable forour purposes may have a low dielectric constant, we propose to use suolimaterials in connection with material of a high- 60 er dielectricconstant. Thus, a mixture of Wax and the previously noted materialsMycalex" and Condensa C in powdered form may be used. Other combinationswill suggest themselves in accordance with our teaching. 65

The dielectric constant of the liquid or substantially solid materialsmay also be modified, e. g., it may be raised according to our inventionby adding thereto a powdered or pulverized metal. I

'I'he invention may be practised by disposing the insulating materialwith high dielectric constant only in a part of the space providedbetween the metal electrode and the subject to be treated. It is merelynecessary in such a case The diso that the part of the space containinga medium of small dielectric constant, for example airis small whencompared with the 'part of the space containing the medium of highdielectric constant.

Several embodiments of the invention are illustrated in diagrammaticform and -partly in section in the accompanying drawing, Figs. 1 to 7,wherein like parts are designated by like reference numerals.

Referring now to the drawing, numeral I indicates the metal electrode.In the embodiments shown in Figs. 1 to 6, this electrode is joined withan electrode rod or handle 2 which may be provided at one end with athreaded extension b engaging the electrode. At the other end of thehandle 2 is provided an internal thread a. Numeral 3 in Figs. 1, 2 and 4designates an insulating coat or layer which covers the handle, the edgeof the corresponding electrode and the outer side of the electrode I. Inthe embodiment shown in Figs. 3 and 5, the electrode I and the handle 2are completely covered with the insulating coat, while in the embodimentaccording to Fig. 6 the insulating coat 3 is placed only on theelectrode handle or rod 2. Numeral 5 indicates the insulating materialdisposed between the subject 6 and the corresponding metal electrode I.The size of the electrode depends somewhat on the amount of poweravailable, and it should not be so large-that the requisiteconcentration cannot be obtained. Within the limits thus imposed, thesize may be in proportion to the part to be treated, but in any eventthe area of the electrode should preferably be some- I`what less thanthe area of the tissue to which it is presented in the treatment.

A substantially rigid insulating material 5 may be used in conjunctionwith the embodiment Fig. 1. One side of this material may be providedwith a metallic coat which may be sprayed thereon, as is indicated inFig. 1 by the reference numeral 4. The layer of insulating material thusprovided with a metallic iilm or coat may be soldered to thevelectrode.As shown in Fig. 2, the metal electrode I may also be joined with therelatively rigid insulating material 5 by a threaded connection byprojecting the threaded portion b of the electrode handle through themetal electrode I and extending it into the threaded boring II in theinsulating material 5. The structure illustrated in Fig. 3 includes themetalelectrode I which is enclosed in the insulating envelope 3. 'I'heflexible or yieldable bag or container 'I holds the insulating material5 which in this case may be in the form of a powder. The embodimentindicated in Fig. 4 shows an electrode arrangement wherein one side ofthe metal electrode I may be suitably roughened or etched or may beprovided with suitable grooves c. The insulating layer 5 may consist inthis case of a yieldable insulating material such as wax and the like.The roughened or grooved surface c facilitates the attachment of theyieldable layer of insulating material to the metal electrode I.

Fig. 5 shows an embodiment employing a yieldable envelope I containing aliquid insulating material such as water which is placed between theinsulation covered electrode I and the subject 6.

The structure illustrated in Fig. 6 comprises a relatively rigidcontainer I0 holding the insulating material 5 as shown. The metalelectrode I contactsV the insulating material. The container AIll* maybe closed by means of a cover or lid 8 kand the latter may be joinedwith the rod orhandle 2,by means of a screw 9. If compressibleorvyieldable insulating material 5 is used in conjunction withthestructure shown in Fig. 6, the same may be' compressed by shifting thehandle 2relative to the cover or lid 8 and setting the structure in anydesired position by means of the screw 9. This particular structure alsopermits adjustment of the space between the electrode and the subjectunder treatment when rigid insulating material is employed in thecontainer I0.

The arrangement according to Fig. 7 includes an external yieldableenvelope I2 in which may be disposed the yieldable electrode I asindicated. The electrode handle is not shown in this gure; it will beclear, however, that the handle projects from the envelope I2. Thisouter envelope Contains the yieldable inner envelope 'I holding theyieldable insulating material. Numeral 6 designates the subject to betreated as in previously described gures.

Changes may be made within the scope and spirit of the claims whichfollow. We have dened in these claims what we believe to be new in theartl and it is expressly understood that we intend to use and employ anyand all'such structures and embodiments that may be covered by theseclaims, subject only to the showing of the prior art.

We claim: i

1. In an electrode arrangement for applying to a body electricoscillations of very'high frequency, the combination of a metalelectrode and a layer of dielectric material for spacing said electrodeaway -from the body to which said oscillations are applied, said layerhaving a dielectric constant aproximated to that of the body to whichsaid oscillations are applied, which dielectric constant is higher than10 but does not exceed the order of substantially constituting arelatively small resistance for the electric eld applied to said body.

2. In an electrode arrangement for applying to a body electricoscillations of very high frequency, the combination of a metalelectrode and a` layer of non-fibrous substantially airfree dielectricmaterial having a thickness of at least 10 mm. for spacing saidelectrode away from the body to which said oscillations are applied,said layer having a dielectric constant which is higher than 10 but doesnot exceed the order of substantially 100- constituting a relativelysmall resistance for the electric field applied to said body. l

3. In an electrode arrangement for applying to a body electricoscillations of very high frequency, the combination of a metalelectrode and a layer consisting of liquid dielectric materialforspacing said electrode away from the body to f which saidoscillations are applied, means for attaching said dielectric materialto said metal electrode, said layer having a dielectric constant whichisV higher than 10 but does not exceed the order of substantially 100constituting a relatively small resistance for the electric fieldapplied to said body i 4. In an electrode arrangement for applying to abody electric oscillations of very high frequency, the combination of ametal electrode and a. layer of dielectric material, consisting of asolid material in comminuted condition, for spacing' said electrode awayfrom the body to dielectric material for spacing said electrode awayfrom the body to which said oscillations are applied, said layer havinga thickness of at least 10 mm. and a relatively high dielectric constantsubstantially equivalent to that of thev body to which the oscillationsare applied which is preferably higher than 10 but does not exceed theorder of substantially 100 constituting a relatively small resistancefor the electric field applied to said body, said dielectric materialserving to substantially equalize the effects of said oscillations inthe surface and interior of such body whereby deleterious deilection ofthe lines of force on passing from said electrode arrangement to thebody is substantially avoided and the ratio of internal penetration ofsaid oscillations to surface eiect thereof is increased.

6. In an electrode arrangement for applying to a body electricoscillations of very high frequency, the combination of a `-metalelectrode and a layer of dielectric material, consisting of a mixturecontaining a solid material in comminuted condition and a uid substance,for spacing said electrode away from the body to which said oscillationsare applied, said layer having a dielectric constant which is higherthan 10 but does not exceed the order of substantially 100 constitutinga relatively small resistance for the electric neld applied to saidbody.

J OHNNES PTZOLD. PAUL BE'I'Z.

